The present invention relates to ultrasonic imaging, and it provides particular advantages when used in ultrasonic harmonic imaging, in which the image signal is acquired at a harmonic of the transmitted fundamental signal.
In ultrasonic harmonic imaging, the strength of the harmonic echo signal varies as a non-linear function of the intensity of the transmitted beam. In the past, transmitted power levels have been set according to the intensity levels reached at the central transmit line. The actual transmitted power levels will generally be slightly reduced at steering angles other than that of the central line, due to the angular response rolloff of the transducer elements and the reduced effective aperture size for noncentral transmit lines.